﻿#include <stdio.h>
int main()
{
    char A, B, C, D, E;
    int score;
    scanf_s("%d", &score);
    if (score < 0 || score>100) {
        printf("Input error!\n");
    }
    else
        if (score <= 60) {
            printf("E\n");
        }
        else
            if (score < 70) {
                printf("D\n");
            }
            else
                if (score < 80) {
                    printf("C\n");
                }
                else
                    if (score < 90) {
                        printf("B\n");
                    }
                    else
                        if (score < 100) {
                            printf("A\n");
                        }

    return 0;
}